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2,669,753 RED VALVE HrNG wm O B :0U NC 9 NRnNul AEI B T 2 MBA RUSh RNC O Er Hmwa d R n F .1

Feb. 23, 1954 METHOD OF PROD STEM WITH Patented Feb. 23, 1954 rL TRATE-S fEAYTEINT @FiF-.1GB

,METHQD QFPRQDUCING RUBBER Covlinnn` VALVE STEM WITH ,QQMREN.

SATING-g RUSHING lFrankrlti Hofmann, Brooklyn, N. Y.,rassig4nor `to 1 Scovill'- Manufacturing Company, Waterbury, pwConnWa corporation o Connecticut c Application ,March ,2, 1950, `Serial,llfl- 142,220

v The present invention relates lto tire valve sten'isof the typeolnprs'ing a metal'sternprovided atome end with `a ruloloer,hasey flangevby means of Whchthe Valve `stem is adapted to be attached` to na1-'tire tube by vulcanization-or the like.` ljInthe course of attaching a rubber base flange to a metal valve s tem ,jthe stem is "insertedinto a mold cayity with a rubber slug and, as the mold closes; the mold pin engageslthe end` of the stem to seal oli' bthe `opening therein,`1'.he slugfows around the stern andlls the mold cavity and the thickness ofthe rubberhase is determined loytheextentr to which jthe mold pin, which is "adjustable, protrudes `beyonfx the mold closing pla-te. "In manufacturing operations, however, 'somejsliglit Variations `in the length of `themetal valve stems may occur andbecause of such Variations and the Vfact thatI the molcl pin `may `Wear andthe Inoldfrnay havebecogne Warpeijtheremis feverv present 'the dangerthat4 the" Y rubber pase flanges will not be uniorm. A'For exarnple, in exlltrerne cases where the valve stezn'is toojsh'ort for vccsntact with the mold pin, rubber willjin'djits Way into `the bore of fthe stem and must be subsequeritly removed by a wire 'brush or the like; where the stem is too long, the rnold ic mgeris prevente@ ,from fully. @losing the mold with the' result Llelllyth las@` flange isexcessively tllckfand .has ,@.leslve @ash atiitsperipheral,edge'whihymusl be trimmed away. fWheiefthe stem is too long Eller@ lszwalso,zpitesentilw tanger Ofleormns the 'mold sealing n. "k

among, the, objects ,0f the ,present rubber' hase, xfalve stem wherein the ,aforemena method oflfornging rubber' baseyalvekhstems wherein the tolerances between. the" cut--off` ring wand vthe 4length of the` Valve aloof/'e the outpff @all` be irmrassd; 1w toprovidea method ,'ofzforming; valve stems ofthe character set forth wherein `the adjustment of the mold `nin `may, Qbe

less accurate than presentpraotice dotates With- ,Qutdversely ,afftetlng L the l reslltne product: l (4) to proyde a methodlo forming valvestems ofthecharater"set forth `Wlgekljen mold Warp- `ins', andiwearfdoes @not affect, haplnlihr'ollrl; the

Amold; (5) ,to provide `arubloer baseyalife `stern wherein maximum diameter Qfhoremaz/be main rl-flinefd all@ the, lnflatins rate. through ihefvalv ,Stem` thereby increased; .s 6) to Awmode a f valve stem `in `which g fthe 'core ,drilling machining is bmnlea Since; no ressstrdrillus,inquired: 1.1"?)

are'jthe following: ffl) to,provide Va bodyins fm?. ilivenn lli; is a metallic yalyelstenl 241,` hav c 2 but an insignificant ajlditional costfor the resultnsimpmfed valve." stem! The l foregoing and" other Y objects ofthe `ingen- .tiorl not .Snelilal enumerated@ faoll'l llSh by ,introducing a Uslidable,snugffittingwbus ng mathe 'bore of the metal vane stem mj the 'end Whereat the'ruhb'er bya'serllange tfolje attached, with `a portion ,of ithe pushing ,protruding beyond said end,hthejbu'slhingj b'ein'g sc -postioneg vthat when molding the,loas'euarrlge` the 'nold' pin will a,ummatlwlly` Slide thehuslllna lnl912QSiliQ.1 as `the mold closes` to proidain effecj'lafvalve*stem of ideal length `for cooperation*withjthe rnold. The invention Willloe` better understo"` ron the detailed descripcion,whwhiouows het Fig; 2 shows `a;vvwletvsnfxrilar` to (Fia lgwith the Wing Fig. llsliows a view similar towFig. M2. aprilie@ to arl-1 en weed scale arfor s`t 'f 1 Fig. lshws, ori

ere

g Darts th portion l0 consistingof t1 assembled pagrtbs"v lvl, 4for edwth a moldM `Cavity kconfigura on uas Qthefomoll ',p'ermse forms ,nailart of ,th rsentimention.

.Adapt/diosa mount@ d, .Within thelmallnavity t I s a bf, 4srufalce,or"Shoulder 'Tadaptclito w at 4n nlthe scaling l sboulderA l G.

age the .pinch cut-off- 28 with a portion of said bushing initially protruding beyond said end, the bore at the protruding end of the bushing being preferably tapered as indicated at 2l for complemental engagement by the tapered shoulder ill on the pilot pin. The seating of the shoulder 2i against the tapered bore portion 2l in the bushing provides a pinch or cut-off which prevents entry of rub-` ber into the bore of the valve stem when the mold closes.

In manufacturing operations some slight variation in the length of the metal valve stem 2t may occur and because of such variations there is ever present the danger that the seal between the Shoulders 2| and 2l Will not take place to insure rubber base flanges of uniform thickness. For example, in extreme cases Where the valve stem is too short for contact with the mold pin the rubber' will find its Way into the bore of the stem and must be subsequently removed by a wire brush or equivalent means; Where the stern is slightly longer than required, the mold cover is prevented from fully closing the mold with the result that the` base and fiange is excessively thick. However, by employing a bushing such as 26 which normally protrudes beyond the end of the valve stem a sufficient distance to be engaged by the mold pin and provide a seal there- With, the mold pin upon the closing of the cover will force the bushing into the valve stem bore to the correct amount and thereby provide in effect, a valve stern of ideal length .for the particular mold.

In forming a rubber covering and base flange on a valve stem such as 2li, with the mold equipn ment as illustrated in Figs. 1 and 2, a valve stem is placed in the mold, a rubber slug 2S is then placed on the top of the mold body overlying the mold cavity, and the mold cover is then brought down into engagement With the mold body. As the mold closes the slug Wili start to flow but the mold pin Will contact and seal on the bore of the bushing Z6 before the mold is actually closed.

As the mold continues to close, the bushing is.

forced into the valve stem by the mold pin, its nal position being determined by the setting of mold pin Which protrudes beyond the flat surface 23 of the cover. The rubber Within the mold after being subjected to the proper ternperature and pressure for a predetermined period of time becomes vulcanized and firmly attached to the valve stern` and the rubber covered valve is then removed from the mold and has the `form as shown in Fig. 3.

Where the invention is to be applied to a tire yvalve stem 24a as shown in Fig. 4, intended for motor trucks, airplane Wheels and the like, the rubber base flange is of a character to only encompass the base flange Zlib of the valve stem .and extend therefrom. Accordingly, the mold cavity is made to conform to the particular valve stem structure or other bored member to Which .a rubber base flange is to be attached and as shown in Fig. 4 the mold body part ld is formed with a sealing shoulder Ita for engaging and providing a pinch cut-of with a shoulder 2Q formed on the valve stem 24a. Here again, to insure the ideal length for a valve stem for cooperation with the mold pin to provide a flange of proper thickness the rubber base ilangeen gagingk end of the valve stem is provided with a bushing 26 identical in all respects and intended to function in precisely the same manner as the bushing 26 hereinbefore described.

The bushing 26 mounted in the valve stem 2t,

Cir

in addition to providing a means for compensating for variations in the length of the valve stems may be made to serve the additional function of providing a seat for the spring cup support of the conventional or standard Schrader valve insides. In this connection the innermost end 3l) of the bushing may provide the shoulder for supporting such spring cup. As shown in Fig. 5, I prefer to form the inner end of a bushing 26a With a counterbore 3| to provide a shoulder 32 which Will serve as a seat for the spring cup support of a valve insides.

The method of molding a rubber flange on a tubular valve stem of the type shown in Figs. 1 to 3 and the construction of the resulting product possesses the following advantages: it prevents the rubber from gaining access to the bore of the valve stem, thereby eliminating the Wire brush thread cleaning and internal rubber cleaning operations; the tolerances between the cut-off shoulder and the length of the stem below such shoulder can be increased; the position of the mold pin in relation to the cover can be allowed to vary Within reasonable tolerances; Warpage of the mold does not adversely aiect the pinch cutoil; more uniformity of rubber base flanges resuits; a maximum diameter through the valve stem consistent with strength and standard dimensional limitations are possible, thereby in suring faster ination through the valve stems especially When the long valve insides are used; the core drilling machining is simplified since no recess or offset drilling operations is required thereby decreasing tool costs and insuring bet- 7 ter concentricity for the various diameters of the bore. Many of the foregoing advantages also accrue to the type of valve stem shown in Fig. fl.

While I have shown and described certain preferred embodiments of my invention, and the manner in which they are to be carried out, I do not Wish to be limited to the specific details of construction shown and described since these may be varied within the range of engineering 5 skill without departing from the spirit of the invention as claimed.

What I claim is:

l. The method of automatically compensating for variations in the length of a bored member in moulding a plastic covering onto one end thereof in a mold press having a. cover plate provided with a sealing pin for the bore in the member nxedly carried by said cover plate, said method comprising slidably mounting a snugtting bushing into the bore of said member at the end thereof which is to be covered having a portion of said bushing protruding beyond said end, placing said member and plastic material in said mould, supporting said member against axial movement in the mould and engaging said protruding end of the bushing by the sealing pin and sliding said bushing into the bore of the member by the sealing pin as the cover plate moves to close the mould.

2. The method of moulding a rubber flange on a tubular metal stem formed with a bearing surface in a mould having a cover plate provided with a sealing pin for the bore in the stem, said method comprising slidably mounting a snugfitting bushing into the bore of the stem at the end thereof whereat the ange is to be formed having a portion of said bushing protruding beyond said end, placing said stem with a mass of rubber in a mould having a sealing shoulder for accommodating said bearing surface on the stem,

and engaging said protruding end of the bushing by the sealing pin and sliding said bushing into the bore of the stem by said sealing pin as the cover plate moves to close the mould.

3. The method of insuring the sealing of the bore of a valve stem when moulding a rubbei` base flange on a valve stern which is slightly shorter than required for a particular mould cavity, in a mould having a movable cover plate, said method comprising increasing the initial effective length of the stem slightly beyond the length of a stem intended for accommodation by the particular mould cavity, by inserting into the bore of said stem at the end thereof wher-eat the rubber base flange is to be attached, a displaceable, snug-fitting bushing leaving a portion of said bushing protruding beyond said end, and engaging and moving said exposed end of the bushing into the stem by the mould cover plate as it moves to close the mould.

4. The method of forming a valve stem consisting of a rubber base fiange attached to a hollow metal member, which comprises assembling in a mould having a movable cover plate, a tubular metal valve stem having a snugly tting sleeve in and protruding from the bore of the tubular metal valve stem at the end thereof which is to be provided with the rubber base flange, together with a mass of rubber, and engaging said protruding end of the sleeve by the cover plate of the mould and forcing said sleeve into the bore of the valve stem by said cover plate as it moves to close the mould.

FRANK R. HORMANN.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,847,414 Smith Mar. 1, 1932 2,028,592 Crowley Jan. 21, 1936 2,135,569 Ellis Nov. 8, 1938 2,135,570 Ellis NCIV. 8, 1938 2,145,218 Broecker Jan.. 24, 1939 2,329,346 Geil? Sept. 14, 1943 

